During the operation of the engine, the actuators of the air charging system, such as the EGR valve actuator(s), the VGT actuator and the intake valve actuator, are used to regulate a number of important output parameters of the air charging system, for example the pressure inside the intake manifold, the oxygen concentration inside the intake manifold and the pressure inside the exhaust manifold, according to performance and emissions requirements.
It is known that an internal combustion engine is equipped with an air charging system provided for supplying air into the combustion chambers. The air charging system basically includes an intake pipe that conveys air from the ambient environment to an intake manifold in fluid communication with the combustion chambers. In the intake pipe there may be an intake valve having an actuator arranged to move a valve member that regulates the mass flow rate of the air, and a compressor provided for increasing the pressure of the air in the intake manifold. The compressor may be driven by a turbine that rotates by receiving exhaust gasses from an exhaust manifold in fluid communication with the combustion chambers. In order to regulate the rotational speed of the compressor, the turbine may be a variable geometry turbine (VGT) having an actuator arranged to alter the angular position of the turbine vanes. The air charging system may further include one or more exhaust gas recirculation (EGR) pipes for recirculating a portion of the exhaust gasses from the exhaust manifold back into the intake manifold. Each EGR pipe is generally provided with an EGR valve having an actuator arranged to move a valve member that regulates the mass flow rate of the recirculated exhaust gasses.
To perform this function, these actuators are conventionally controlled by an electronic control unit (ECU) according to separated and uncoordinated control strategies, which enable each individual actuator to be operated in any desired or required position, independently from one another. However, the effects generated on the output parameters by the actuators of the air charging system are generally strictly interdependent and have mutual interactions, so that the separated and uncoordinated control strategies may be affected by low accuracy, especially during fast transients. Moreover, this conventional control approach needs a vast calibration activity.